View Program - 2022 Population, Evolutionary, and Quantitative Genetics Conference

The mosquito, Aedes aegypti, is the primary species that transmits dengue, zika, chikungunya, and yellow fever worldwide. Currently, insecticides (e.g., pyrethroids) remain the most commonly used method to decrease the population size of these pests and reduce disease incidence, but resistance is becoming a widespread problem.

Knockdown resistance (kdr) is a specific type of pyrethroid resistance caused by one or more single nucleotide polymorphisms (SNPs) in the voltage-gated sodium channel gene (vgsc) that alter the vgsc protein in a way that decreases the effect of pyrethroid on mosquito survival. Many SNPs that contribute toward the kdr phenotype have been identified worldwide. Two common SNPs in the Western Hemisphere are F1534C and V1016I.

We previously reported the rapid evolution of two kdr haplotypes in a population of mosquitoes from Iquitos, Peru. The rapid rise of kdr haplotypes was dominated first by the increase in individuals carrying only the Cys1534 resistance SNP and later by individuals carrying both the Cys1534 and Ile1016 resistance SNPs. Here, we further examine this phenomenon by interrogating polymorphic regions of the vgsc gene that are not functionally associated with kdr resistance. This information will help to elucidate existing questions about the dynamics that underlie kdr resistance in this mosquito. Do resistant individuals arise from one or multiple common ancestors? Are the resistance haplotypes selected from standing genetic variation or from de novo mutations? Does population structure of the mosquito within the city impact the spread and interactions between the two resistance SNPs? Gaining a better understanding of the evolutionary dynamics that govern the rise of insecticide resistance will aid in improving resistance management.

Tracking the origins and rapid rise of two distinct insecticide resistance haplotypes